Mechkah was shot in the thigh by police during the knife rampage in Turku, 170 kilometres (105 miles) west of the capital Helsinki, and was treated for his wounds at a local hospital before a planned move to a prison hospital, police said.

The nationality of the new suspects was not clear, police said, because they gave contradicting information.

They told Finnish officials they were Algerian citizens but had earlier told Swedish authorities that they were from Morocco. It was unclear when they were in Sweden.

A picture taken with a smart phone shows the Market Square in Turku. Photo: STR/AFP/Getty Images

The main suspect arrived in Finland last year, but his application for asylum was denied, police said.

Earlier, the German Interior Ministry said the man entered Germany at the end of 2015, leaving there in early 2016.

A video grab taken from Twitter shows officials standing in a street in the Finnish city of Turku where several people were stabbed. Photo: JUHA RIIHIMAKI/AFP/Getty Images

He did not apply for asylum in Germany, the ministry said.

Investigators and the main suspect's lawyer Kaarle Gummerus have said they were not aware of a motive for the attack, in which most of the victims were women.